"Cecilia... isn't fitting in and is spending too much time with an imaginary friend, named Natasha. A psychologist is recommended, but Dahlia declines and tells Cecilia to ignore Natasha. Although Veeck had said it was claimed, Dahlia discovers the Hello Kitty backpack in the laundry room's garbage. Cecilia later finds it in the elevator."

"and in the elevator, her mother's ghost braids her hair and comforts her"

"...momentarily horrified with a malfunction in the elevator, the weird behavior of his daughter"

From a description of Dark Water (Japan 2002)

"Intending to escape, she rushes into the elevator, fleeing apparently from the apparition of Mitsuko. But as the elevator door closes she sees that the figure pursuing her is in fact her own daughter..."

"Yoshimi sacrifices herself by staying on in the elevator to appease Mitsuko's spirit and pretending to be Mitsuko's mother. The elevator ascends and Ikuko follows, but when the doors open, a flood of murky brown water rushes out and nobody emerges."

Quoting: Anonymous Coward 33628542

just think..what if.. these ghosts/projections mentioned in the film became reality for Elisa as these invisible men, made by this company doing augmented reality stuff ..would fit in the bigger picture as well..